Retin-A Combined With A Boots Scar Serum and Laser Vein Treatment?

I've two questions about Retin-A, i have been using it for seven weeks and having good results, but before i started using it i was using a boots scar serum,twice a day which worked quite well, but since using the Retin i stopped using the serum as i'm not sure whether it may hinder it,so would it be ok to start with the serum again in the mornings? My second question is i'm getting some laser work on some thread veins on my face and need to know if i need to stop the Retin before treatment,Tymv